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Google and other search engine sites can lead to climate change riches … but not every search does. Researchers need to take a caveat emptor — buyer beware — approach and select their search terms with precision to avoid being led to error-prone websites.

Imagine that you’re curious about climate change but know little about it.

You might turn to the world’s most popular search engine, Google, and begin typing keywords, such as “climate change facts.”

What will you learn?

As of early May, a search for “climate change facts” will lead you to the webpage climatechangefacts.info. There, you’ll be told that the link between carbon dioxide and Earth’s temperature is unproven, that many scientists agree that the sun is responsible for rising global temperatures, and that Earth may soon begin to cool.

Each of these claims is contradicted by the broad scientific understanding of climate change, namely that burning fossil fuels is releasing carbon dioxide to the atmosphere and causing the planet to warm.

Yet in May, climatechangefacts.info was Google’s top-ranked result for the search “climate change facts.” That put the site ahead of the webpages for the U.S. Environmental Protection Agency, The New York Times, and the Pew Center on Global Climate Change. The precise wording of the search phrase is of course critical.

A recent Yale Forum analysis indicates that misleading websites constitute more than 10 percent of high-ranking results for climate-related searches. Some of those sites make wildly inaccurate claims about cosmic rays and the benign nature of carbon dioxide. One top-ranked religious site explains that warming might return Earth to the conditions present in the Garden of Eden.

But search experts said that because of the large volume of searches that search engines must process, and because of the ever-changing behavior of Web publishers, such sites will likely continue to turn up in search results. Because of those challenges, one expert said, information seekers still need the skills to recognize credible information for themselves.

The Analysis on Climate Change Searches

When people need answers from a search engine, most of them turn to Google. Data released by comscore.com in March showed that the company controlled 66 percent of the search engine market. Users conducted more than 11 billion Google searches that month. So the search engine is likely a leading conduit for people curious about climate change.

But how common is a case such as the search for “climate change facts,” in which an information seeker will find inaccurate information about the topic in Google’s top search results?

Next, The Yale Forum examined the websites that appeared on the first page of results for each search string, 980 webpages in all. The sites were classified based on the type of information offered, such as support for the scientific consensus, news about the topic, or skeptical claims.

The results suggest that often, Google leads people to accurate information about climate change. Fifty-two percent of the 980 sites contained clear statements in line with the vast majority of peer-reviewed climate science evidence. For example, if you had searched for “climate change myths” in early May, you would have found this Environmental Defense Fund site, which says, “The most respected scientific bodies have stated unequivocally that global warming is occurring, and people are causing it.”

Wikipedia pages made up another 5 percent of the search results. Information in the free encyclopedia’s articles can change frequently as Web users edit them. But at the time of The Yale Forum review, the pages about climate change generally supported the scientific consensus.

News sites accounted for another 27 percent of search results. The results often included articles published by reputable news or science-oriented news organizations, led by The New York Times (8 percent of news articles), National Geographic (7 percent), and Scientific American (5 percent).

The Yale Forum also found news articles that contained inaccurate information. A search for “anthropogenic global warming,” for example, led to this column in The Telegraph, which claims that the world is cooling and that “the tide is turning against Al Gore’s Anthropogenic Global Warming theory.”

In addition, The Yale Forum review showed that non-news sites promoting skeptical viewpoints accounted for 11 percent of search results. Unsurprisingly, a search for terms such as “climate change hoax” directs users to several skeptical sites. For example, infowars.com, which appears on the first page of results for that search, describes carbon dioxide as a “benign, life giving molecule” that has been miscast as “an environmental hazard in what will soon be discovered to be the hoax of the century.”

But skeptical viewpoints also resulted from searches for seemingly neutral keywords. Six of the 11 websites on the first page of results for “anthropogenic global warming” offered a skeptical perspective. Likewise, searches for “global warming,” “global warming news,” “global warming causes,” and “global warming consensus” turned up high-ranking skeptic sites, along with many sites that support the bulk of the scientific evidence.

A search for “evidence of global warming” led to the website of the Institute for Creation Research, a religious organization that promotes creationism. The site claims that current warming, perhaps caused by cosmic rays, “may be returning our global climate closer to that prevalent in the Garden of Eden.” The site ranked in first place in results for that search, ahead of NASA’s climate page.

‘There Are No Editors’

The Yale Forum analysis suggests that in general, Google users will find accurate and credible information about climate change. But skeptical viewpoints turn up far more often in search results than they do, for example, in the peer-reviewed scientific literature.

How does a creationist website rise higher in Google’s ranking than NASA’s climate page? And how does a site that claims the sun is causing global warming beat the U.S. Environmental Protection Agency’s website?

Understanding the answer to those questions requires a bit of knowledge about how Google works. To help people find information, the company’s computers first locate and retrieve webpages. Then, Google examines those pages and creates a giant index of the Web, akin to the index in the back of a textbook. When you enter a search query, Google’s algorithms determine which pages are the closest match.

The company does not disclose the exact rules its algorithms use to rank webpages. But one important factor is a site’s popularity, measured by the number of other sites that link to it.

“If a lot of people, or some respected people, are pointing at a particular website, that helps it rank better,” said Danny Sullivan, editor-in-chief of Search Engine Land, an industry publication.

Take climatechangefacts.info, the top-ranked site that claims the sun is causing global warming. If you type the address into Yahoo Site Explorer, you will see that the site, operated by an individual in Arlington, Va., has about 8,500 inlinks, or links from other pages. In contrast, the Environmental Protection Agency’s page on global warming facts has 44 inlinks.

“Google’s not trying to assess if what it lists is factually correct,” Sulllivan said. “There are no editors, in the human sense, reading all these pages.”

The Challenge of Scientific Vocabulary

Sites will also rank higher if they are friendly to search engines, or search-engine optimized. For example, most search engines assume that the words that appear in a page’s address and title and near the top of the page indicate what the site is about, so they give more weight to those words.

As a consequence, a page with the address climatechangefacts.info is well-poised to achieve a top ranking on a Google search for “climate change facts.” In fact, the site also holds the No. 1 position in search results by a Google search engine competitor, Microsoft’s Bing.

In contrast, many science-oriented pages are not search engine optimized. And they often use specialized vocabulary that members of the public are unlikely to search for, said Jamie Callan, a professor of computer science at Carnegie Mellon University.

Part of the explanation for the search engine results is that scientists are rewarded only for publishing in academic journals, Callan said. Few have received training in Web publishing or in search engine optimization.

“Scientists probably do need to spend more effort expressing their results in a way that the general public can understand them and creating the webpages that people can find,” he said.

Callan added that members of the public also need better training in how to find reliable and authoritative websites.

“We need to be more discerning consumers of information,” he said.

No ‘Final Victory’

Meanwhile, can search engines do a better job of pointing the public toward credible sites?

A Google spokeswoman, who insisted on anonymity because she is not a Google executive, said the company is always looking for ways to improve results. “Last year, we made 500 changes to the algorithm to improve search quality,” she said.

Prabhakar Raghavan, the head of Yahoo! Labs, the company’s research division, said that tilting search results, for instance, toward government and university websites might improve the quality of information for climate-related searches.

But he said that biasing the algorithm in that way also could disrupt results on other topics. “There is no mechanism for saying that the university or the government is always the best source,” he said.

He described search results as a game between search engine companies and Web publishers. The companies are working to provide better search results, he said, and some of the Web publishers are trying to subvert those results for commercial or political purposes.

Occasionally, a search engine company will take action against such a publisher. For example, The New York Timesreported in February that J.C. Penney was using questionable linking tactics to drive Google searchers toward its site. In response, Google demoted the company’s ranking.

Search engine companies also monitor whole classes of queries, such as searches related to candidates for political office, Raghavan said. But he said that each time a search engine enacts a new set of ranking policies, Web publishers work rapidly to subvert those policies so that they will again achieve high rankings.

“I don’t believe there will ever be a final victory,” he said.

As with so much else, things may in the end come down to caveat emptor, let the buyer,or in this case the researcher, beware.